Aircraft

Ford funds study on eVTOL commuting emissions, and it doesn't go well for Ford

An 'artistic rendering' of a future VTOL air commuter
An 'artistic rendering' of a future VTOL air commuter
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An 'artistic rendering' of a future VTOL air commuter
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An 'artistic rendering' of a future VTOL air commuter

A Ford-funded study by the University of Michigan has examined the environmental credentials of electric VTOL aircraft for commuting, compared to both regular and electric cars over a range of commuting distances. The results paint an interesting picture of future mobility.

Published in the open-access Nature Communications journal, the study assumes that eVTOL flying cars will be powered by electricity from regular power plants rather than renewable sources – and that the VTOLS we're talking about will have the capacity to convert to efficient winged flight after the high energy draws of vertical takeoff and landing, which is a reasonable assessment.

The researchers took a bunch of realistic parameters to feed into their equations, assuming that the aircraft will look something like what's currently being developed by the likes of Joby, Airbus, Boeing and Lilium, among numerous others. Thus, they were able to take a reasonable stab at working out what the vehicles would weigh, their lift-to-drag ratios, battery-specific energy, and how much energy they'd be using during the different stages of flight: takeoff, hover, climb, cruise, descent and landing.

Presumably Ford funded this study hoping for eco-ammunition against a future competitive threat, but things didn't quite go that way – unless you're planning to fly less than 22 miles (35 km). That's the point at which a single-occupant eVTOL trip became cleaner than a single-occupant combustion car, taking urban traffic into account as well as the lack of traffic in the air.

Go further, say 62 miles (100 km), and the emissions savings pile up. Even with a fully loaded eVTOL carrying 4 passengers measured against a combustion-engine car with the average 1.54 occupants on board, the VTOL had emissions 52 percent lower than the car.

Even more surprisingly, over the same length of journey, the 4-passenger VTOL created some 6 percent fewer emissions than even an electric car. And this on top of offering massive time savings thanks to their three-dimensional traffic busting capabilities.

The researchers seem not to have expected the outcome. "To me, it was very surprising to see that VTOLs were competitive with regard to energy use and greenhouse gas emissions in certain scenarios," said Gregory Keoleian, senior author of the study and director of the Center for Sustainable Systems at U-M's School for Environment and Sustainability."VTOLs with full occupancy could outperform ground-based cars for trips from San Francisco to San Jose or from Detroit to Cleveland, for example."

Indeed, one of the biggest possible shifts we could see thanks to eVTOLs, once they're fully certified and in regular use, is a shift away from urban living for those who can afford to take these services to work. Why not live by the beach if you can replace a 20-mile, hour-long slog through city traffic with a 60-mile, 30 minute air taxi ride?

The study appears in the journal Nature Communications.

Source: University of Michigan

20 comments
Towerman
Google just started its drone delivery service in Australia, we are getting one step closer each month to for-fill an EVTOL future !
Nobody
Did they consider ALL the emissions in the building and maintenance of a electric VTOL aircraft? How about its service life?
paul314
So how many VTOLs can you have before air traffic gets as bad as ground traffic?
ProclaimLiberty
The likelihood of charging with renewable energy such as solar increases as more such vehicles will be in private hands and residences are converted accordingly.
MerlinGuy
It's strange that ground vehicles are restrained by real world parameters but VTOL calculation get to take absolute best case scenarios as their functioning data. Who will be the owners of eVTOLs? Ride shares. Which means you have to add cost of getting to the client, finding a permitted landing spot. Waiting for clearance to take off. Flying to and from a recharging station much more often.
SimonClarke
a couple of quick comments, an aircraft in flight uses very little energy, there is no rolling resistance for starters. A sailplane in flight only needs a little lift to keep it airborne for hours. add that to the direct flight approach, you don't need to follow existing ground routes. control wise, there are several things already in place. for conventional aircraft you fly in a height range depending upon your direction. This is designed to prevent aircraft flying into one another. with computer controlled flight systems you air taxi will not only communicate with a central control system but also with other air taxis in your area. also, if all of the air taxis fly at the same speed, then there will not be any conflicting traffic issues.
ei3io
VTOL vehicles have practically everywhere for landing potential even on water with flotation. The traffic in 3D space is many times more capable of absorbing vehicles by orders or magnitude more than the much smaller area of narrow roadways. Air traffic can use many layers of controlled routes and or random 3D free flow with self flight computer coordination. When air traffic is uniformly distributed even with every car in the air at once it will still be thousands of feet separation vs bumper to bumper on roads.
Trylon
@SimonClarke, there may be no rolling resistance, but there is a lot of aerodynamic drag at the speeds necessary to maintain lift. Sailplanes can stay aloft pretty well without power, but they're completely at the mercy of air currents, updrafts and winds. You can't really plan to go anywhere you want with them.
Lsaguy104
The study doesn't take into account the pollution created cleaning up the aircraft after each flight. Unless they can come up with software able to predict and counteract convective activity they're going to be flying vomitoriums. The airlines struggled for 20 years until they got an airplane that could fly above the weather. It was only then that people would readily fly. If the aircraft stays in the lower atmosphere it's going to be subjected to some pretty serious turbulence almost every day between the hours of 10 am to 6 pm. Now add weather and you're going to have days and times when the aircraft just can't fly. That doesn't happen to road vehicles except in very rare instances.
Jose Gros
The evolution of a previous project by the University of Michigan, for the 'Urban Car Contest', that installed an OMC Wankel RCE, 45 HP, 530 cc per chamber, single rotor, air cooled housing, charge cooled rotor, double side and peripheral intake port, seems inspired the German 'Smart'. So, we can expect continuation of the Michigan idea about VTOL taxi. Good news!